Traditional fastSPICE tools (e.g., HSIM, UltraSim, NanoSim, FineSim) all make a number of accuracy tradeoffs in order to get higher performance. This generally works very well for digital designs where a 5% to 10% inaccuracy is acceptable and worth 10x-100x+ performance and capacity. High-performance analog and RF circuits require much tighter accuracies in order to get correct behavior let alone accurate performance information. “Analog Mode” or tight tolerance settings in most traditional fastSPICE simulators can get you within 2% to 5%. That’s better but generally not accurate enough, and as you tighten traditional fastSPICE simulators to near-SPICE accuracy, you get near-SPICE (or worse) performance.

Analog FastSPICE is completely different than traditional fastSPICE tools. It makes absolutely no approximations, simplifications, abstractions, etc. It runs the original device equations, so it really gets full SPICE accuracy – down to the specified SPICE noise floor (e.g., reltol – typically 0.1%). The waveforms for every node on every run are identical to those produced by traditional SPICE simulators (e.g., HSPICE and Spectre). The only difference is performance. For multiple-hour and longer runs, Analog FastSPICE is consistently 5x-10x+ faster than traditional SPICE. That means it turns a week run into a day run, a day run into a few-hour run, and a few-hour run into a 30 minute run. Berkeley Design Automation stands behind the 5x-10x performance claim versus any simulator that produces full SPICE accuracy to the noise floor.

Because Analog FastSPICE really is full SPICE accurate, designers can use it for post-layout designs, variation analysis (corners and Monte Carlo), and verifying circuits with package inductance and/or transmission line effects. Analog FastSPICE also has vastly superior convergence which gives it 5x-10x higher effective capacity than traditional SPICE. This means it can converge and run full SPICE accurate transient simulation on circuits that no one would dream of running with traditional SPICE (e.g., full 802.11 transceiver, SerDes, flash, etc.). The tool routinely runs circuits with >1M total elements and >200K transistors.

The most impressive thing about Analog FastSPICE is that it actually works as advertised. It reads standard SPICE netlists, standard SPICE models, requires no special inputs or tuning (it doesn’t even have a facility for block-level tuning), produces standard output waveform files, and is integrated into Cadence Virtuoso ADE. Just plug it in and get the same results 5x-10x faster.

Don’t trust me. Look at what the customers on BDA’s web site have to say. Contact them and ask them. Design teams can contact us and we’ll prove it on their circuits.

Over 40 customers have benchmarked Analog FastSPICE (AFS) on over 150 circuits versus probably every simulator out there in the last 10 months. AFS consistently beats every simulator by at least 5x when true full SPICE accuracy is the standard. Our accuracy standard is very exacting. If a customer identifies any discrepancy between Analog FastSPICE and their traditional SPICE simulator, our first step is to tighten the accuracy on both simulators. More times than not the traditional SPICE simulator waveforms move to the AFS results. Designers are amazed and immediately start wondering about their current simulator. If a discrepancy remains after setting very tight tolerances, we debug it until we find the source. We can take this approach and deliver these results in all cases because we solve the original device equations. If it is a bug in AFS, we fix it and deliver a fully regression-tested release generally within a week or two.

Most of Berkeley Design Automation’s early customers are Japanese companies because consumer IC suppliers were extremely concerned about PLL noise. Our first product was the world’s first (and still only) closed-loop, non-approximate PLL noise analyzer – called PLL Noise Analyzer (PNA). We focused that product on the Japanese market (where we have always had direct sales, BTW). Since Japanese semiconductor companies are notoriously exacting, our first 10 customers compared PNA results directly to silicon (because no other simulator can do this analysis). PNA delivers absolute accuracy to silicon to ~3dB. Running the PLL through a series of settings in silicon and PNA to “wash” out the modeling inaccuracies, PNA consistently tracks silicon to within ~1dB, i.e., if the tool says your PLL noise is getting better (or worse), then that’s what is really happening.

Berkeley Design Automation released PNA about 2 years ago with our transient engine (now Analog FastSPICE) and our RF engine (now RF FastSPICE) under-the-hood. By taking this approach we were able to prove and mature these two engines before taking them to the general market as standalone tools that work on any type of circuit. Our original PNA customers are now all Analog FastSPICE and RF FastSPICE customers as well. We announced Analog FastSPICE and RF FastSPICE at DAC last year and have had an incredible level of interest worldwide. We are rapidly signing up and announcing new customers including most recently Spansion, Atheros, Newport Media, and LG Electronics. You can expect to see many additional new customer announcements in the coming weeks and months.

Whew. Sorry for the long response, but sometimes the short answers do not give a complete picture. Thanks for your well wishes. Stop by and see us at DAC if you are there.

I appreciate the thorough answers and can see why you are so excited about Analog FastSPICE at Berkeley DA.

The skeptic in me is now challenging the other SPICE providers to ante up their customer success stories in the FastSPICE segment. Let's hear from Mentor (ADiT), Cadence (UltraSIM), Magma (FineSim PRO), Synopsys (HSIM, Nanosim) and Nascentric (AuSim). Do your products compete with Analog FastSPICE? If so, what customers say so?

I'll drop by your booth at DAC to see how much buzz your booth and suites are generating.

It seems you may have missed an important point about Analog FastSPICE – it doesn’t compete in the traditional fastSPICE segment. We often refer to traditional fastSPICE as “digital fastSPICE” because that was the original target segment and remains its strong suite. HSIM, NanoSim, UltraSim, ADiT, FineSim – they are all digital fastSPICE simulators in that they tradeoff accuracy for performance. These simulators are great for digital designs and memories where 2%,5%, and even 10% inaccuracy compared to SPICE is “good enough.” Giving up that accuracy enables them to run sometimes 100x or more faster than traditional SPICE. Digital fastSPICE simulators will continue to do very well in digital and memory applications. We tell customers who don’t need real full SPICE accuracy (i.e., to the SPICE noise floor, not within a few percent) that they should use digital fastSPICE. Analog FastSPICE only makes sense for analog and RF circuits that need absolutely full SPICE accuracy.

As its name implies, we believe Analog FastSPICE defines a new category of circuit simulator. Traditional SPICE will continue to be best for block-level analog, traditional fastSPICE (a.k.a., digital fastSPICE) will continue to be best for digital and memory designs, and Analog FastSPICE is the best tool for complex blocks and top-level analog and RF circuits.

Good question. I should have stated that we believe traditional SPICE will continue to be the primary simulator for verifying “simple blocks,” where we define simple blocks as those with <1K elements or <1-hour runtime. Above those levels, Analog FastSPICE (AFS) is consistently 5x-10x faster. Below those levels, it may not be.

The primary reason we believe traditional SPICE will be the primary simulator for simple blocks is value. Analog FastSPICE may not provide 5x the speedup on simple blocks and the value of any speedup is generally much less for short runs (e.g., cutting 5 days to 1 day is generally much more valuable than cutting 5 min to 1 min – even if there are a lot of 5 min iterations). Pricing is certainly part of that value equation. AFS pricing is more aligned with digital fastSPICE simulators than with traditional SPICE simulators because of the value it provides. Given that companies have very large investments in traditional SPICE simulators, those tools will be around for years regardless Analog FastSPICE or any other next-generation simulator. That investment will migrate to the place where it provides the highest relative value which is on simple circuits.

If a circuit has less than 1000 elements, can BDA's Analog FastSpice be slower than Spectre/Hspice or just as fast as Spectre/Hspice?

As we know, there is not much multi-rate in a tiny analog circuit. So Analog FastSpice's multi-rate technology doesn't help. Furthermore, if the circuit consists of mostly Bsim3 or Bsim4 models, then the device model evaluation time dominates simulation time because a small circuit matrix is very fast to solve. According to your press releases, Analog FastSpice evaluates original device equations. So can we conclude that it has no advantage over Spectre/Hspice under these circumstances? I don't see any. Here I am assuming all the simulators take the same number of timesteps. If a simulator is faster because of less timesteps, that doesn't count. Less timesteps leads to worse accuracy.